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Galápagos Finch Speciation Unfolds Rapidly

Researchers call attention to the speciation of a Galápagos Finch, a process seemingly accelerated by hybridization with a non-native finch.

Speciation is an evolutionary process in which small genetic changes lead to an entirely new species. For the first time, researchers have been able to watch this process unfold in the field. Normally this process happens over such a long time scale that it would be extremely difficult to witness and record. Darwin’s Galápagos Finches are already known for speciation that occurred long ago, but now excitement is rising over a new species of Finch that has just evolved.

Researchers have been studying a population of Galápagos Finches on a small island called Daphne Major for years to observe speciation. In 1981, a male Large Cactus Finch, a species from Española and non-native to the island, appeared and began to mate with native Medium Ground Finches. To the researchers’ surprise, these offspring were fertile. Now, after almost 40 years the population has grown. Professor Roger Butlin explained:

It’s an extreme case of something we’re coming to realise more generally over the years. Evolution in general can happen very quickly.

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This is an image of the Big Bird lineage, which arose through the breeding of two distinct parent species: G. fortis and G. conirostris. Credit: P.R. Grant

Now the population has reached approximately 30 individuals from that one Large Cactus Finch 40 years ago. The Cactus Finch, native to Española, would have had to fly 65 miles to reach Daphne Major. The new population has been nicknamed the “Big Bird population” for their large size relative to the native finches.

One of the even more surprising finds came when researchers ran genetic testing on the Big Bird population to see if they truly were a different species. They found the species had not bred with any of the other finches on the island, due to the difference in mating calls, and has resulted in reproductive isolation. Professor Leif Andersson of Sweden’s Uppsala University commented:

The surprise was that we would expect the hybrid would start to breed with one of the other species on the island and be absorbed…we have confirmed that they are a closed breeding group.

The hybridization caused by a lone bird almost 40 years ago has now created a large and rapidly evolving species, showing the forces of natural selection beyond random mutation. It is unclear what effect this will have on Daphne Major’s ecosystem–only time will tell.

Featured Photo: Medium Ground Finch (Geospiza fortis). Credit: Tommy Hall/Island Conservation
Source: BBC

About Emily Heber

Emily is a recent graduate from UC Santa Barbara with a BS in Zoology. As a student, she discovered that she had a passion for the conservation of endangered species and their ecosystems. Her background in informal education has allowed her the opportunity to share her passion for animals with others, something she seeks to continue doing while working with the communication team. In her spare time, Emily enjoys exploring the amazing hiking trails found in Santa Cruz and tries to SCUBA dive whenever possible. Emily is excited to join the Island Conservation team and to help share the amazing work that is being done here.

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